Process of deposition



April 25, 1939. H. c. DAVIS 2,155,932

PROCESS OF DEPOSITION Filed April 26, 1958 2 Sheets-Sheet 1 1H lllln lINVENTOR ATTORNEY Howard C. Dauls April 25, 1939. H. c. DAVIS- PROCESSOF DEPOSITION Filed April 26, 1958 2 Sheets-Sheet 2 837/05 N08: 331V 19HINVENTOR Howard C. DGUIS -452M- ATTORNEY Patented Apr. 25, 19392,155,932

UNITED STATES PATENT OFFICE PROCESS OF DEPOSITION Howard C. Davis,Elizabeth, N. J.

Application April 26, 1938, Serial No. 204,481

7 Claims. (01. 41-42) The invention herein disclosed relates to a riesof coils through which a refrigerant is process for treating articles bydepositing a subcirculated. When so cooled, all moisture above stanceupon the surfaces of articles tobe treatthe saturation point of the airat the lower temed. More particularly, the invention relates to peratureis removed.

a process for effecting the deposition of sub- The air, after theremoval of the mositure, 5 stances in finely divided or atomized form tois passed through a heating chamber wherein secure a homogeneous anduniform deposit on the temperature of the air is raised substanthesurfaces of articles. tially. This may be accomplished by employing Theprocess essentially comprises utilizing a in the heating chamberordinary heating coils 0 carrier substance for conveying the substanceto through which either steam or hot water passes, 10 be deposited infinely divided form to the article. the latter being preferable as it ismore readily This carrier substance is one that is in a gaseouscontrolled. The elevation of the temperature of. state under normalatmospheric conditions of the air raises the saturation point of the airtemperature and pressure and the carrier utiand correspondingly reducesthe relative hulized is one that is substantially chemically inertmidity. 15 with respect to the substance to be deposited and The heatedair is circulated into contact with the article to be treated. Thesubstance to be the liquid substance in finely divided form. Indeposited is either normally in a liquid state or some instances thecirculation of air may be if normally in a solid state, it is dissolvedin a effected by a fan or blower, in others it may be liquid. Incarrying out the process, the temeffected by aVenturi tube arrangementin which 20 perature and relative humidity of the gaseous the liquidsubstance is forced through a fine carrier is fixed at a predeterminedvalue. The atomizing jet so that an injector effect is obliquidsubstance is maintained at a temperature taine'd. In both instances theliquid substance below the boiling point thereof and it is divided isdivided into a finely divided or atomized form into a finely dividedform. The temperature of and thus presented to the moving heated air.

the gaseous carrier is maintained substantially The atomized liquid istaken up by the heated above the temperature of the article upon whichair until the liquid content. of the air corresponds the liquidSubstance s to be deposited and the to its saturation point at thetemperature of gaseous carrier is circulated to successively bring theair.

it into contact with the liquid in finely divided The air is thencirculated at a very low ve- 30 form and then into contact with thearticle. In locity through a treating chamber that contains this way theliquid is converted into a state in the articles upon which the liquidis t be Which it ys t e laWS p ng to gases and posited. The relativetemperature conditions of carried to the article by the gaseous thecarrier air and the articles is such that upon The q d is reconvertedinto the liquid S a coming into contact with the articles the liquid 35and deposited p the le When brought into carried by the air isreconverted into the liquid C t W th t e article A u m, hOmO- state anddeposited uniformly over the surface e s coating s u obtained v t of thearticles. In most instances the articles face of the article and wherethe liquid is a sot b o t d 111 b moved in continuous hl n and theliquid is v porated from the surcession through a treating chamber andthe time 40 face of the article, a homogeneous, uniform coatof passagethrough t treating Chamber may ing of the dissolved matter remains onthe surb regulated, The carrier air will be circulated face of thearticle. and recirculated in the cycle described which in- In most usesto Whi h t e process is app1i eludes the treating chamber. The amount ofcable, air may be us s the gaseous eerrierthe deposit on an articlewill, of course, depend 45 When used as the gaseo Carrier, the air isupon the moisture content of the carrier air, fi st dehumidified y y ofthe methods new the relative temperatures of the air and the p y d forreducing the moisture content f articles and the time the articleremains in the air. For example, the air may be circulated over treatingchamber.

or through beds charged with an absorbent hav- This process has manydifi'erent applications. 50 ing an aflinity for moisture such as calciumIt is suitable for impregnating materials, for chloride, silica gel oraluminum salts. Or the film coating exposed surfaces of materials,dyemoisture content of the air may be materially reing fabrics, etc.Examples of. some of the uses duced by lowering the temperature of theair to which the process is applicable are given as by circulating theair over or through a sebelow. Others will be suggested by the examples.55

One purpose for which the process is especially suitable is etchingglass. In this process the carrier gas used is air and the substanceused for etching the glass is hydrofluoric acid. Throughout the processthere is no chemical change effected in the hydrofluoric acid, except asis effected in its action upon the glass, but its physical charactersare changed in that it is converted from the liquid state into a statein which it follows the laws pertaining to gases and it is reconvertedand deposited on the glass as a liquid. The entire process is carriedout in apparatus provided for the purpose and in the manner heretoforedescribed air is dehumidified and then heated. It is caused toflow in acycle including the heating chamber wherein the heating of the air iseffected, a chamber in which the hydrofluoric acid is vaporized and thetreating chamber. The carrier gas is continuously circulated andrecirculated in this cycle and the glass articles to be etched passthrough the treating chamber in continuous succession. The hydrofluoricacid is thus uniformly deposited over the surfaces of the articles andthe glass is etched by the action of the acid on the glass.

One form of apparatus that may be used in etching glass in this manneris illustrated in the accompanying drawings in which:

Fig. 1 is a longitudinal section through the treating chamber of theapparatus;

Fig. 2 is a transverse section of the same taken on the line 2-2 of Fig.1;

Fig. 3 is a fragmentary, sectional, side elevation taken on the line 3-3of Fig. 2; and

Fig. 4 is a partially diagrammatic illustration of the connections ofthe apparatus.

The apparatus illustrated in the drawings includes a heating chamber A,an atomizing chamber B, and a treating chamber C, all of which arearranged to form a continuous circuit so that the carrier air may becirculated in a cycle through these chambers successivelyin thedirection indicated by the arrows. The heating chamber A and theatomizing chamber B are contained in a cylinder having two sections laand lb. The lower end of the section la. is closed and on the upper endthere is a flange which is connected to a similar flange on the lowerend of the section lb. The upper end of the section lb is also providedwith a flange to which a cover I is secured.

The heating chamber is in the section la of the cylinder and it isseparated from the atomizing chamber B by a diaphragm 2 having a Venturitube 2a extending from the center thereof and forming the air passagebetween the heating and atomizing chambers. The diaphragm 2 is securedbetween the flanges of the upper and lower section of the cylinder. Adrain 2b is provided in the diaphragm for draining acid from the chamberB into the chamber A which also forms a sump for the excess acid. Withinthe chamber A there is a heating coil 3 through which hot water obtainedfrom a boiler (not shown) is continuously circulated, the supply beingindicated by a pipe 4 and the outlet from the heating coil beingindicated by pipe 5. This heating coil is provided for the purposes ofheating the circulating carrier air.

Near the upper end of the section lb of the cylinder, which forms theatomizing chamber, there are provided two baffles 5 and 6 which causethe circulating air to move transversely of the cylinder and which actto remove any entrained liquid from the air, that is, any of the liquidentrained in globular form. At the upper end of the cylinder I, there isa lateral hollow boss 1 which is connected through flanges 8 to theupper end of the treating chamber C. Through the passage provided by theboss 1 and the opening 9 in the wall of the heating chamber with whichit communicates, a circular trough-shaped element In extends. Thistrough-shaped element extends from the far wall of the atomizing chamberto the far wall of the heating chamber and is open along its upper edge.The carrier air on reaching the top of the atomizing chamber flows overthe edge of the trough, into the trough, through the trough and againover the edge of the trough into the treating chamber.

The treating chamber is rectangular in section. It is connected at thelower end to the heating chamber through a flange connection I I to ahollow boss I 2 extending from the heating chamber and through which thetreating chamber C communicates with the heating chamber A. Throughthese connections the air thus circulates from the treating chamber tothe heating chamber, through the heating coil 3, through the Venturitube 2a in the diaphragm 2 into the atomizing chamber and through thetrough-shaped conduit l0 back to the treating chamber. It wil1-be notedthat the cross-sectional area transverse to.

the flow of air in the treating chamber is many times larger than thearea of either the heating chamber or the atomizing chamber transverseto the direction of flow in these chambers. In View of this fact, whilethe air may have a substantial velocity in the heating and atomizingchambers, it will have a relatively low velocity in the treatingchamber. The velocity of the air in the heating and atomizing chambersis so taken that the air moves through the treating chamber at a verylow velocity.

The air is caused to flow in the cycle including the heating chamber A,the atomizing chamber B and the treating chamber 0, by virtue of theforce of the acid issuing from an atomizing jet M, the opening fromwhich extends into the lower end of the Venturi tube 2a. This atomizingjet may be any one of several known types and the atomization may beeffected if desired by the employment of centrifugal forces. The acidutilized in etching the glass is forced through the jet I l. On beingforced through this jet the acid is atomized, driven at high velocitythrough the Venturi tube 20. and causes the air to flow in the cyclejust mentioned. The air may also be caused to flow in the cycle byemployment of a fan or blower where desirable.

Extending through the treating chamber C, there is a continuous conveyorl5 that is stretched over pulleys l6 and H which are outside of thetreating chamber per se but within extensions [8 and I9respectively'extending from the ends of the treating chamber. Thisconveyor belt is driven in the usual Way by a motor (not shown)connected to one of the shafts on which a pulley is mounted. Theconveyor belt, which is made up of a plurality of individual beltsformed from wire Wound in a helix, extends through openings 20 and. 2!in each end wall of the treating chamber. The arrows adjacent theconveyor belt indicate the direction in which the conveyor is normallydriven although it may be driven in either direction.

The extension l8 from the end wall of the treating chamber is likewiserectangular in crosssection. On the upper side of this extension andcovering an opening 22 through the upper wall thereof and extending fromside wall to side wall,

there is mounted a hood 22a on which there is a stack 23 having a damper24 therein. Another rectangular opening 25 constituted by a series ofslots is provided across a receiving table 26 mounted in the extensionI8. A stack 21 communicates with this opening in the table, the stackpassing through an opening 28 in the lower wall of the extension I8. Thestack 21 is enlarged as at 28 and contains a heating coil 29 throughwhich hot water or steam is circulated. Air enters the lower end of thestack 21 through an opening 30 in which there is a regulating damper 40.

By virtue of the transfer of heat from the coil 29 to the air, there isan upward flow of hot air through the stack 21, across the extension I8and through the stack 23. The flow of hot air across the extension I8forms a hot air curtain slightly higher in temperature than the gases inthe treating chamber which prevents any of the air in the treatingchamber from passing out to the atmosphere. At the same time, there isobtained an unobstructed opening through which the glass articles can bemoved onto the table 26 and from there onto the conveyor belt I on whichthey are carried through the treating chamber C and delivered to adelivery table 3| in the extension I9. The extension I9 is identical inall respects with the extension I8 and a curtain of warm air is likewiseformed across the extension I9 to prevent the flow of the acidladenedair in the treating chamber out into the atmosphere. The coil 29 in thestack 21 is supplied wtih hot water or steam through a supply pipe M andthe hot water or steam is returned through a return pipe 42. Similarconnections are provided for a heating coil 43 in the stack 44 utilizedin conjunction with the extension I9 and for forming the curtain of hotair adjacent the end of this extension.

Acid is supplied to the atomizing jet I4 from acid tanks 45 and 46. Theacid tank 45 has a circumferential jacket 45a that is connected to thereturn pipe 5 from the hot water heating coil 3. The hot water from thecoil 3 enters this jacket and maintains the acid therein warm. An outletfrom the jacket 45a is connected by a pipe 41 to a similar jacket 48 onthe tank 46. From the jacket 48 the hot water is returned to the boilerthrough a return pipe 49. These tanks supply acid to the acid atomizingjet I4 successively. While the acid from one tank is being forcedthrough the jet I4, the other tank receives the acid that is not takenup and carried by the air and that drains into the heating chamber A.When one tank is emptied, acid is supplied from the other tank, and thefirst tank becomes the tank that receives the return acid. For thisreason the two tanks are connected in common to the several pipes fordelivering acid from the tanks and returning acid to the tanks. Theatomizing jet I4 is thus connected to a. supply pipe 56 which isconnected in common to pipes 5! and 52 that lead to a point adjacent thebottom of the tanks 45 and 46 respectively.

In the pipe 5I, there is a valve 53 and in the pipe 52 there is a valve54 so that either tank may be opened to the pipe 5|] or shut oiTtherefrom. The acid not taken up by the air is collected on the bottomof the heating chamber A and passes through a return pipe 55. Thisreturn pipe is connected in common to pipes 56 and 51 which arerespectively connected to the tanks 45 and 46. In the pipe 56 there is avalve 58 and in the pipe 51 there is a valve 59. The acid is forced outof the tanks and through the jet I4 by compressed air that is deliveredto the top of the tank thus pressing upon the acid and forcing it upeither the pipe 5| or 52 depending upon which tank is connected to theacid atomizing jet I4. This compressed air is delivered from a source ofcompressed air through a pipe 60 that is connected in common to pipes GIand 62 which in turn are respectively connected to the tanks 45 and 46.In the pipe 6I there is a valve 63 and in the pipe 62 there is a valve64 so that either one or the other of the tanks can be connected to thesupply of compressed air. When a tank is receiving the return of theacid, that tank is vented to the atmosphere and for this purpose thereis provided a vent pipe 65 which is connected in common to a pipe 66 anda pipe 61. The pipe 66 is connected to the tank 45 and the pipe 61 isconnected to the tank 46. In the pipe 66 there is a valve 68 and in thepipe 61 there is a valve 69.

In operation, air that has been fixed with reference to its temperatureand relative humidity is introduced into the apparatus. A heating mediumis supplied to the coils 29 and 43 to form curtains of hot air acrossthe openings provided by the extensions I8 and I9 of the treatingchamber. The conveyor belt I5 is caused to operate by rotation of thepulleys. Hot water is supplied through the pipe 4 to the heating coil 3in the heating chamber A. From this coil the hot water flows to thejacket 45a. surrounding the acid tank 45 and from the jacket 45a throughthe pipe 41 to the jacket 48, surrounding the tank 46, and from thejacket 48 back to the boiler by way of the return pipe 49. When the acidis warmed to the desired temperature, substantially below the boilingpoint, the apparatus is ready for operation. When this occurs, valves59, 53, 63 and 69 are opened. Valves 68, 64 and 54 are closed. With thisrelation of the several valves, the top of the tank 45 is connectedthrough the pipe 6I to the supply of compressed air represented by thepipe 65. The pipe 50 supplying the atomizing jet I4 is connected throughthe pipe 5I to the tank 45. Likewise, the tank 46 is connected to thevent pipe 65 through the pipe 61. It is closed off from the compressedair, and it is shut off from the supply pipe 50 by the valve 54. Thetank 46 however is opened to the acid return pipe 55 through the pipe51. The tank 45 is of course closed off from the vent to the atmosphereand from the acid return pipe 55. Under these conditions the compressedair acting upon the upper surface of the acid in the tank 45 forces theacid through the pipe 5I, the acid supply pipe 56 and through the jetI4. As the acid issues from the atomizing jet I4 under pressure and intothe Venturi tube 2a, the air in the apparatus is caused to circulate. Oncirculating, it mixes with the acid that is transformed into a conditionin which it responds to the law of gases and with the air it is carriedaround the baffle 5 and around the bafile 6 and into the trough-shapedelement I0. Any entrained acid will be removed by the bafiles 5 and 6.It will be noted that these baiiles are tilted with respect to thehorizontal so that any of the entrained acid depositing thereon willdrip back to the plate 2 and through the drain therein to the bottom ofthe heating chamber. This liquid acid will thus be returned through thepipe 55 to the tank 46. The mixed air and acid will flow through thetrough-shaped element Ill and into the treating chamber 0.

The glass articles to be etched are moved in continuous succession ontothe table 26 and from there onto the conveyor I so they pass through theconveyor in a continuous series The relation of the circulation set upby the jet through the Venturi tube 20, is such that with respect to thecross-sectional area transverse to the direction of flow of the air inthe treating chamher, the air moves through the treating chamber at avery slow rate, a rate such that the thermal difierence between the airand the glass articles, which are introduced at normal room temperature,is sufficient to create eddy currents in the air so that theacid-ladened air contacts with all surfaces of the glass articlespassing through on the conveyor. The conveyor itself is as stated formedof a series of belts, each of which is a convolute wire in the shape ofa spring, thus providing space through which the acid-ladened air cancontact with all surfaces of the glass. It will be understood of coursethat if the velocity of air in the treating chamber is sufliciently highto prevent the formation of the eddy currents that result by virtue ofthe thermal difference between the air and the glass articles, theacidladened air will no come in contact with all surfaces of the glassand it is for this reason that the velocity of the air in the treatingchamber must be kept very low. Upon coming in contact with the glasswarewhich is at room temperature and a temperature substantially lower thanthe temperature of the acid-ladened air, the acid in the air isreconverted into the liquid state and deposited upon the glassware, andforms a uni form liquid film over the entire surface of the glass. Theair passes from the treating chamber into the bottom the heating chamberbelow the coil 3. This constitutes a cycle of the circulation of thecarrier air and the air is continuously recirculated in this cycleduring the operation of the apparatus.

As the glass articles issue from the extension IQ of the treatingchamber and pass through the curtain of hot air, they may be sprayedwith water to remove the acid if the etching process be sufiicientlycomplete or they may be carried on and further processed. Anything doneafter the glass articles leave the treating chamber will depend entirelyupon the efiect desired on the glass.

When all of the acid or nearly all of the acid is expelled from the tank45, the valves 63 and 53 are closed and the valves 66 and 58 are opened.At the same time, the valves 69 and 59 are closed and the valves 54 and64 are opened. When this is done, the tank 45 is connected to the acidreturn line 55; it is cut on" from the acid supply line 50 and cut offfrom the compressed air line 68 and opened to the vent 65. The tank 46is cut oif from the acid return line 55, opened to the acid supply line58; opened to the air compressor line Bil, and cut oif from the vent 65.The acid is then delivered from the tank 46 and returned to the tank 45.The two tanks are thus alternately utilized for supplying the acid untilall of the acid of both tanks is utilized. All of the parts of theapparatus that carry the acid or with which the acid or acid-ladened aircomes into contact, are of course properly lined with lead. It is to benoted that, with the exception of the conveyor belt, there are no movingparts that come into contact with the acid or acid-ladened air.

From the foregoing it will be seen that by the apparatus hereinabovedescribed, which forms a part of this invention, the process of theinvention may be continuously carried out and a uniform deposition of aliquid substance may be efiected upon the surfaces of articles. Theamount of liquid that is deposited on the articles will of course dependupon several factors including the temperature of the carrier air, thetemperature of the articles, and the speed at which the articles movethrough the treating chamber. The heat supplied to the tanks 45 and 46is insufficient to raise the temperature of the liquid content of thesetanks to the boiling point thereof.

It is essential that the temperature be maintained below the boilingpoint. This is particularly true where the process is utilized fordepositing a solid substance upon articles. In such instance, the solidsubstance is dissolved in the liquid and the process carried out ashereinbefore described, the solution being the liquid that is carried bythe carrier gas. When the liquid is deposited upon the articles andevaporated, the solid dissolved in the liquid remains as a homogeneousdeposit upon the surface of the article.

In a similar manner, a homogeneous coating of wax may be obtained on thesurfaces of articles such as paper, for example. For this purpose, awater soluble wax may be utilized. The wax is first dissolved in waterto form a water solution of the wax. The solution of wax is atomized inthe atomizing chamber and taken up by the air. In the treating chamber,the solvent carrying the wax is deposited upon the paper leaving ahomogeneous deposit of wax on the article when the water is evaporated.

Another application of the process is lacquer coating of variousarticles. When lacquer is used as the vehicle for a pigment, the lacquercontaining the pigment is atomized and the lacquerladen air is deliveredto the treating chamber where it is deposited upon the surface of thematerial to be treated. In this Way, metal, wood, fiber, glass or othermaterials may be given a thin coating of lacquer to prevent tarnish ormold on material subject to such surface conditions.

It is obvious that various changes may be made by those skilled in theart in the steps of the process and the details of the apparatusdescribed above within the principle and scope of the invention asexpressed in the appended claims.

I claim:

1. The process for effecting a uniform deposition of a liquid substanceover the surface of an article which process comprises utilizing acarrier substance that is in a gaseous state under normal atmosphericconditions for conveying the substance to be deposited on the article,the gaseous carrier being substantially chemically inert with respect tothe liquid substance and the article and which process includes thesteps of fixing the temperature and relative humidity of the gaseouscarrier, dividing the liquid substance into a finely divided form,maintaining the temperature of the liquid substance below the boilingpoint thereof, maintaining the temperature of the carrier gassubstantially above the temperature of the article, and circulating thegaseous carrier to successively bring it into contact with the liquid infinely divided form and then into contact with all surfaces of thearticle, whereby the liquid is converted into a gaseous state, mixedwith and carried by the gaseous carrier to the article whereon it isreconverted to the liquid state and deposited on the surface of thearticle on coming in contact therewith.

2. The continuous process for effecting a uniform deposition of a liquidsubstance over the surface of a series of articles which processcomprises utilizing a carrier substance that is in a gaseous state undernormal atmospheric conditions for conveying the liquid substance to bedeposited on the articles, the gaseous carrier being substantiallychemically inert with respect to the liquid substance and the articleand which process includes the steps of fixing the temperature andrelative humidity of the gaseous carrier, dividing the liquid substanceinto finely divided form in an atomizing chamber, maintaining thetemperature of the liquid substance below the boiling point thereof,moving the articles to be treated through a treating chamber,continuously circulating the gaseous carrier in a cycle including aheating chamber to maintain the temperature of the gaseous carriersubstantially above the temperature of the articles, the liquidatomizing chamber and the treating chamber, and maintaining a relativelyslow velocity of the gaseous carrier in the treating chamber, wherebythe liquid substance is converted into a gaseous state, mixed with andcarried by the circulating gaseous carrier to the treating chamberwherein it is reconverted to the liquid state and deposited on thesurface of the articles on coming in contact therewith.

3. The continuous process for effecting a uniform deposition ofhydrgfluoridacid over the surface of a series of glass articles for thepurpose of etching the glass, which process comprises utilizing acarrier substance that is in a gaseous state under normal atmosphericconditions for conveying the hydrofluoric acid to be deposited on thearticles, the gaseous carrier being substantially chemically inert withrespect to the hydrofluoric acid and the glass and which processincludes the steps of fixing the temperature and relative humidity ofthe gaseous carrier, dividing the hydrofluoric acid into finely dividedform in an atomizing chamber, maintaining the temperature of thehydrofluoric acid below the boiling point thereof, moving the glassarticles in continuous succession through a treating chamber,continuously circulating the gaseous carrier in a cycle includingsuccessively a heating chamber for heating the gaseous carrier to atemperature substantially above the temperature of the glass articles,the atomizing chamber and the treating chamber, and maintaining arelatively slow velocity of the gaseous carrier in the treating chamber,whereby the hydrofiuoricacid is converted into a gaseous state andcarried by the circulating gaseous carrier to the treating chamberwherein it is reconverted to the liquid state.

and deposited on the surface of the articles on coming in contacttherewith.

4. The process for effecting a uniform coating of a'soluble coatingsubstance upon the surface of an article, which process comprisesutilizing a carrier substance that is in the gaseous state under normalatmospheric conditions for conveying the coating substance in finelydivided form to the article, the gaseous carrier being substantiallychemically inert with respect to the coating substance and the articleand which process includes the steps of fixing the temperature andrelative humidity of the gaseous carrier, dissolving the coatingsubstance in a liquid solvent, dividing the solution into a finelydivided form, maintaining the temperature of the solution below theboiling point thereof, maintaining the temperature" of the gaseouscarrier substantially above the temperature of the article to be coated,circulating the gaseous carrier to successively bring it into contactwith the solution in finely divided form and then into contact with thearticle, and maintaining a relatively slow velocity of the gaseouscarrier past the article, whereby the liquid solution is converted intoa gaseous state and carried by the gaseous carrier to the article to becoated whereon it is reconverted to the liquid state and deposited onthe surface of the article on coming into contact therewith.

5. The process for effecting a uniform coating of a soluble coatingsubstance upon the surface of an article, which processcomprises-utilizing a carriersubstance that is in the gaseous stateunder normal atmospheric conditions for conveying the coating substancein finely divided form to the article, the gaseous carrier beingsubstantially chemically inert with respect to the coating substance andthe article and which process includes the steps of fixing thetemperature and relative humidity of the gaseous carrier, dissolving thecoating substance in a liquid solvent, dividing the solution into afinely divided form, maintaining the temperature of the solution belowthe boiling point thereof, maintaining the temperature of the gaseouscarrier substantially above the temperature of the article to be coated,circulating the gaseous carrier to successively bring it into contactwith the solution in finely divided form and then into contact with thearticle, whereby the liquid solution is converted into a gaseous stateand carried by the gaseous carrier to the article to be coated whereonit is reconverted to: the liquid state and deposited on the surface ofthe article on coming in contact therewith, and evaporating the solventfrom the surface of the article.

6. The continuous process for effecting a uniform coating of a solublecoating substance over the surface of a series of articles which processcomprises utilizing a carrier substance that is in a gaseous state undernormal atmospheric conditions for conveying the coating substance infinely divided form to the articles, the gaseous carrier beingsubstantially chemically inert with respect to the coating substance andthe article and which process includes the steps of fixing thetemperature and relative humidity of the gaseous carrier at apredetermined value, dissolving the coating substance in a liquidsolvent, dividing the solution into a finely divided form in anatomizing chamber, maintaining the temperature of the solution below theboiling point thereof, moving the articles in continuous successionthrough a treating chamber, continuously circulating the gaseous carrierin a cycle including successively a heating chamber for heating thegaseous carrier to a temperature substantially above the temperature ofthe articles in the treating chamber, the atomizing chamber and. thetreating chamber, and maintaining a relatively slow velocity of thegaseous carrier in the treating chamber, whereby the liquid solution isconverted into a gaseous state, mixed with the gaseous carrier andcarried to the articles to be coated whereon it is reconverted to theliquid state and deposited on the surface or" the articles on coming incontact therewith, and drying the articles to remove the solvent.

7. The continuous process for effecting a uniform coating of a solublewax over the surface of a series of articlesm hichwrocss comprisesutilizing air as a carrier gas for conveying the Wax in finely dividedform to the articles and treating chamber, the atomizing chamber and thetreating chamber, and maintaining a relatively slow velocity of thecarrier air in the treating chamber, whereby the liquid solution isconverted into a state following the action of gases, mixed with thecarrier air and carried to the articles to be coated whereon it isreconverted to the liquid state and deposited on the surface of thearticles on coming in contact therewith,

and evaporating the solvent from the surface of 10 the articles.

HOWARD C. DAVIS.

